Stock markets in Dubai and Qatar ended lower on Thursday, hit by blue-chip shares trading ex-dividend, while the Saudi index retreated ahead of an OPEC+ meet.
Saudi Arabia's benchmark index lost 0.7%, with Al Rajhi Bank falling 0.8% and Saudi Telecom Company down 2.7%.
OPEC, Russia and other oil producers meet on Thursday to decide whether to keep April output steady or increase it as they weigh a recent price rally against uncertainty about the economic recovery.
With oil above $60 a barrel, some analysts have predicted that the OPEC+ group of producers will increase output by about 500,000 barrels per day (bpd) and also expect Saudi Arabia to partially or fully end its voluntary reduction of 1 million bpd.
Dubai's main share index dropped 0.8%, with its largest lender Emirates NBD losing 2.2%, as it traded ex-dividend.
Among others, blue-chip developer Emaar Properties retreated 1.4%, a day after registering sharp gains.
On Tuesday, Emaar said it was buying out minority shareholders of its shopping centre unit, less than a decade after floating shares in the company.
In Abu Dhabi, the index eased 0.1%, hit by a 1% fall in Emirates Telecommunications Group.
Elsewhere, the Qatari index fell 0.4%, dragged down by a 5.6% drop in telecoms firm Ooredoo and a 3.6% decrease in United Development Company as they traded ex-dividend.
Outside the Gulf, Egypt's blue-chip index closed 0.5% lower, driven by a 4.1% fall in tobacco monopoly Eastern Company.
Eastern Company's board approved the sale of 35.4 million treasury shares held.